Which of the following is a biological control method?

Releasing sterile males is a recognized biological control method primarily used to manage pest populations. This technique involves introducing sterilized males into a pest population. When these sterile males mate with females, the resulting eggs do not hatch, thereby reducing the overall reproduction rate of the pest species. This method exploits the natural mating behaviors of the pests and can lead to a significant decline in the population over time without the use of harmful chemicals.

In contrast, the other options refer to different types of control methods. Installing barriers involves physical measures to prevent pests from accessing crops or other areas, which is a more mechanical approach rather than biological. Crop rotation is an agricultural practice aimed at reducing pest prevalence through changes in planting locations and crop types, but it does not directly involve biological agents. Using traps is a method to capture and kill pests, which is more akin to physical or chemical control rather than biological intervention. Each of these methods serves a purpose in pest management, but only releasing sterile males fits the definition of a biological control method by using the pests' own reproductive processes against them.